e2e: Bump driver.wait timeouts to 3s
e2e: Bump driver.wait timeouts to 3s

It seems occasional Travis load necessitates even longer timeouts,
especially for the first test case:

https://travis-ci.org/mbland/custom-links/jobs/259492338

mbland/url-pointers,mbland/custom-links,mbland/url-pointers,mbland/url-pointers,mbland/custom-links,mbland/custom-links